Cushioning mechanism



y 1938- L. M. CLARK 2,116,189

CUSHIONING MECHANISM Filed March 9, 1937 2 Sheets-Sheet l M'Ww;

ATTORNEY y 3, 1938. L. M. CLARK 2,116,189

CUSHIONING MECHANISM Filed March 9, 1937' 2 Sheets-Sheet 2 INVENTOR L ZA FML ATTORNEYS atented May 3, 1938 CUSHIONING MECHANISM Leverett M.Clark, Snyder, N. Y., asslgnor to Waugh Equipment Company, New York, N.Y.,

a corporation of Maine Application March 9, 1937, Serial No. 129,797

' 7 Claims. (01. 267-4)) This invention relates to trucks of the typeused on railway vehicles, such as freight cars, and is concerned moreparticularly with a novel cushioning and shock absorbing device to beemployed with springs for supporting the bolster of such a truck withrelation to the side frames. The new device is a friction mechanism ofthe snubber type, which absorbs and dissipates portions of the energy offorces applied thereto, so that it limits the amplitude of the verticalmovements of the car resulting from track irregularities, etc., anddampens harmonic oscillations that occur at certain critical speeds oflocomotion. Its use thus improves the riding qualities of the car andsub stantially reduces damage to both ladings'and the car structure.

The new device is of simple compact construction and it is of such sizeand shape that it may be employed to replace one of the helical springsordinarily used for supporting the truck bolster above the side frames.It may, accordingly. be installed in standard rolling stock withoutchange either in the bolster or side frames.

In one form of embodiment of the invention, the device includes a casinghaving an internal friction surface of generally conical form, apinrality of shoes having friction surfaces engaging that of the casing,and an actuating plunger having an enlarged flanged head. The shoes areconnected operativelyto the plunger by two'different means. one meansacting to cause the shoes to move into and out of the casing with theplunger and the other insuring that the shoes will maintain the properspacing circumferentially of the plunger.

For a better understanding of the invention, reference may be had to theaccompanying drawings, in which:

Figure 1 represents a side elevational view, partly in section, of atruck embodying the invention;

Figure 2 is a sectional view on the line 2-2 of Figure 1;

Figure 3 is a view similar to Figure 2, showing a modified construction;I

Figure 4 is a view similar to Figure 2. showing another modifiedconstruction;

Figure 5 is'a vertical section of the new unit;

Figures 6 and 7 are sectional views on the lines 6-6 and 1-1,respectively, of Figure 5;

Figure 8 is a face view of one of the shoes of the device;

Figure 9 is a sectional view on the line 9-9 of 55 Figure 8; and

tending between the side frames 20 is supported Figure 10 is a plan viewof the shoe shown in Figure 8.

In that form of the new apparatus illustrated in Figure l, the mechanismis shown installed in a standard truck 20 of a railway car, and thetruck has the usual side frames 2| which include tension members 22 andjournal boxes 23. Each side frame is provided with guide columns 24,which define a window 25 at the middle of the side frame, and at thebottom of the window is a seat 26, upon which is mounted the cushioningmechanism 21. This mechanism includes a plurality of helical springs 28and a friction unit generally designatedat 29. and a bolster 30 exat itsends upon the springs 28 and the friction units 29.

The friction unit includes a casing 33 having an open top and a closedbottom provided with a projecting circumferential flange 3 I, and theinner surface of the casing is formed with a frictiongenerating surfacewhich tapers inwardly towards the closed end of the casing. Mountedwithin the casing and projecting beyond the open end of the latter arefriction shoes 32 which are arcuate in section and are provided at theirouter ends with flanges 34 which project outwardly beyond the casing.These shoes have curved outer surfaces which contact with the frictionsurface of the casing and have a similar curvature. On its inner face,each shoe is provided with a plurality of ribs 35 extending transverselyof the shoe, and the opposite surfaces 36, 31 of each rib convergetoward the outer end of the rib.

Within the group of shoes is a plunger 30 which extends outwardly beyondthe shoes and is provided at its outer end with an enlarged head 39.This plunger is provided with ribs 40 having opposite surfacesconverging toward the ends of the ribs, andthe ribs 35 on the shoes arereceived in the troughs between the ribs on the plunger. A spring 4|encircling the casing and shoes bears at its opposite ends against theflange 3| of the casing and the flanges 34 of the shoes, and this springtends to maintain the shoes and plunger in their outermost position. Abolt 42 passing through the closed end of the casing and through acentral bore in the plunger, and provided with a head and nut at itsopposite ends, limits the movement of the plunger and shoes out of thecasing.

Near its upper end, the plunger is provided with a plurality of verticalslots 43, one for each shoe, these slots being equidistantly spacedcircumferentially of the plunger. In the construction illustrated, thereare three shoes and the slots are, accordingly, spaced degrees'apart.Each shoe is provided at its upper end with an inwardly directed lug 44which extends into one of the slots, and the slots and lugs serve tomaintain the shoes at a proper spacing relative to one another, whileallowing the shoes to have a relative movement lengthwise of theplunger.

The device may be installed in a truck in various ways, as, for example,if the truck bolster is normally supported on four helical springs 45,as illustrated in Figure 3, one of these springs may be removed andreplaced by the device 46. In such installation, the bolster restspreferably on the enlarged head of the plunger, and the casing rests onthe seat in the truck frame. The construction shown in Figure 2 is onein which the bolster would ordinarily be supported upon seven helicalsprings 45. The central spring of the group, however, has been replacedas shown by the friction device 46. In the arrangement illustrated inFigure 4, the bolster is ordinarily sup ported on six helical springs45, but one of these springs has been replaced by the friction device46. In any of these constructions, the location of the friction deviceis relatively unimportant, although it may be preferable to mount it ina central position as in the arrangement shown in Figure 2, wherepossible.

In its operation, the device is usually associated with certain helicalsprings which, in combination, support a given load, and this load mayor may not be shared equally by the device and the springs. The eifectof whatever loadthat may be initially'applied to the device is to forcethe" plunger and shoes inwardly of the casing against the combinedresistances of the spring ll and the friction developed between theshoes and the casing. The device is ordinarily assembled with its springunder a substantial initial compression and the pressure of the springactingbetween the fianges of the casing and the shoes forces the latteragainst the plunger, through their coacting angular ribs, while theplunger is restrained by the bolt from being forced out of the casing.The result of this pressure between the coacting angular ribs forces theshoes radially outward against the casing and establishes a. frictionalcomponent that adds to the resistance of the spring. As a load isinitially impressed on the device, as when the weight ofthe truckbolster and the supported portion of the car body is first placed on thedevice and its associated group of springs, the plunger starts to enterthe casing against the combined resistances of the spring 4| and thefrictional component between the shoes and easing. As the plunger andshoes continue to be moved inwardly of the casing, the pressure betweenthe coacting angular ribs, and between the shoes and easing, increasesdue to further compression of the spring and particular- 1y to theinward taper of the casing bore. The pressure continues to increaseuntil the reaction of the coacting angular ribs exceeds the resistanceof spring ll, and the frictional resistances between the coactingangular surfaces of the ribs and between the shoes and casing, whereuponthe shoes will move inwardly with respect to the plunger, therebypreventing a flu'ther increase in resistance disproportionate to theapplied load. The inward movement of the shoes with respect to theplunger will continue to the point where either the maximum load hasbeen applied or the plunger has moved into contact with the closed endof the casing.

Normally, the weight of the truck bolster end of the portion of the carbody supported thereby,

when the car is empty, produces an inward movement of the plunger equalto approximately onehalf of its total possible travel. This gives thedevice the desired capacity to carry loads and, in addition, causes asubstantial adhesional resistance to be built up between the shoes andeasing, this resistance resulting in the generation of friction whichfunctions to produce a dampening effect. The remaining portion of thetravel of the plunger is then available for taking care of lading loadsand f rther compressive movements produced by the application of dynamicforces set up during locomotion. Starting in a statically loadedcondition, the device functions to dampen relative movements of theshoes in contact with the frictional surface of,

the casing.

The number of shoes employed in the device is to some extent optional,but I prefer to use three shoes and that construction is illustrated inthe drawings... These shoes must be maintained in the propercircumferential spacing relative to the plunger and casing, and suchspacing is not 'maintained by the interlocking ribs and recesses on theshoes and plunger, respectively. Accordingly, I have provided theplunger and shoes with interengaging parts, which permit a relativemovement of the plunger and shoes in a direction longitudinal of thecasing, but substantially prevent relative movement circumferentially ofthe casing. In the device as'illustrated, these interengaging parts takethe form of lugs on the shoes and vertically elongated ,slots on theplunger, but it will be understood that various other forms of suchinterlocking parts may be employed. In all forms of the device, however,I provide two different connections; between the shoes and the plunger,one connection preventing substantial relative longitudinal movement ofthe parts, while permitting relative circumferential movement, and theother permitting relative longitudinal movement of the parts, whilepreventing substantial relative circumferential movement. .1

In order that the device may function smooth- 1y without sticking, Iprefer to form the contacting surfaces on the shoes and plunger, atselfreleasing angles, so that after the application of a compressiveforce to the device, the shoes and plunger will move relatively tolighten the contact of the shoes against the friction surface of thecasing, and then will move together outwardly of the casing to theirnormal positions of rest.

I claim:

1. A cushioning mechanism for use on a raflway vehicle truck, whichcomprises the combination of a casing, a plurality of friction shoes inthe casing having surfaces in engagement with a surface thereof, acentral actuating plunger ex- I tending within the group of shoes,resilient means 76 engaging the shoes and tending to force them out ofthe casing, and a pair of separate means operatively connecting theplunger and each of the shoes, one means preventing substantial relativelongitudinal movement of the shoes and plunger, while permitting theirrelative circumferential movement and the other preventing substantialrelative movement of the shoes and plunger circumferentially of thelatter.

2. A cushioning mechanism for use on.a railway vehicle truck, whichcomprises the combination of a casing, a plurality of friction shoes inthe casing having surfaces in engagement with a casing surface, acentral actuating plunger extending within the group of shoes,resilient,

means engaging the shoes and tending to force them out of the casing,interengaging parts on the plunger and each of the shoes preventingsubstantial relative longitudinal movement of the shoes and plunger,while permitting their relative circumferential movement and otherinterengaging parts on the plunger and each of the shoes preventingsubstantial relative movement thereof circumferentially of the plunger.

3. A cushioning mechanism for use on a railway vehicle truck, whichcomprises the combination of a casing,a plurality of friction shoes inthe casing having surfaces in engagement with a casing surface, acentral actuating plunger extending within the group of shoes, resilientmeans engaging the shoes and tending to force them out of the casing,interengaging parts on those portions of shoes and plunger normallylying within the casing, said parts preventingsuhstantial relativelongitudinal movement of the shoes and plunger, and interengaging partson those portionsof the shoes and plunger normally lying outside of thecasing and preventing substantial relative movement of the shoes andplunger circumferentially.

4. A cushioning mechanism for use on a railway vehicle truck, whichcomprises the comblna tion of a casing, a plurality of friction shoes inthe casing having surfaces in engagement with a easing surface, acentral actuating plunger lying within the group of shoes, a series ofinterengaging parts on the shoes and plunger preventingsubstantial'relative longitudinal movement thereof while permittingtheir relative circumferential movement, said series extendinglongitudinally of the plunger, and other interengaging parts on theshoes and plunger preventing substantial relative movement thereofcircumferentially of the casing.

5. A cushioning mechanism for use on a railway vehicle truck, whichcomprises a casing of generally tubular form having an internal frictionsurface, a plurality of friction shoes extending into the casing andhaving surfaces in engagement with said friction surface, an actuatingplunger lying within the group of shoes and having a plurality oflongitudinally elongated slots therein, one for each shoe, interengagingparts on the shoes and plunger preventing substantial relativelongitudinal movement thereof, said parts lying in a row lengthwise ofthe plunger and permitting relative movement of the shoes and. plungercircumferentially of the casing, and

a lug on each shoe entering one of the slots on i the plunger, theengagement of the lug with the walls of its -siot preventingdisplacement of the shoe circumferentially of the plunger.

6. A cushioning mechanism for use on a railway vehicle, which comprisesa hollow casing having a closed end and an open end, the casing beingprovided with an internal friction surface tapering toward the closedend of the casing, a plurality of shoes extending into the casing andhaving curved friction surfaces in contact with the casing frictionsurface, a plunger extending into the group of shoes, a series ofinterengaging parts on the shoes and plunger, said parts being disposedlengthwise of the plunger and preventing substantial relativelongitudinal movement of the shoes and plunger, while permittingrelative circumferential movement thereof, interengaging parts on theshoes and plunger permitting rela tive longitudinal movement thereof,but preventing substantial relative circumferential movement, a springencircling the casing and shoes and acting on the shoes to force theshoes and plunger out of the casing, and means engaging the casing andplunger and limiting the movement of the plunger out of the casing.

'7. A cushioning mechanism for use on a rail- Way vehicle truck, whichcomprises the combination of a generally cylindrical hollow casinghaving a closed end provided with a circumferential flange, the casinghaving an internal friction surface tapering toward the closed end, aplurality of friction shoes extending into the casing andhaving curvedsurfaces contacting with the friction surface of the casing, the outerends of the shoes having projections overlying the casing flange, aspring encircling the casing and hearing at one end against the flangeand at the other permitting relative longitudinal movement thereof,while preventing relative substantial circumferentiaI movement, andmeans engaging the easing and plunger and limiting the movement of theplunger out of the casing.

nnvaan'rr M. bLARK.

